Easier said than done.
Put in dedicated lines between where?
Between every commissary and the DeCA head office? That is a good idea but very costly (and challenging with some commissary locations). However it leaves the DeCA head office wide open for attacks which is where this IRT appears to be based.....
It also creates issues around how card payments are processed, how inventory is managed, how suppliers are engaged etc. All of this opens up avenues for an entertaining and enterprising attacker. Not least of which is that it still leaves a good few risks an IRT would need to handle (malicious insider for example).